Ageing Detection of Encapsulants and Backsheets in the Field via NIR Spectroscopy

Photovoltaic (PV) modules and systems degrade during operation. It is necessary to understand how those mechanisms develop over time and to find precursors that allow an early detection of potential fatal faults. In this work, we investigated the evolution of performance loss rates (PLR) of 6 PV systems exposed in northern Italy for about 11 years, and we characterized 19 PV modules belonging to the systems via near infrared (NIR) spectroscopy to identify encapsulant and backsheet types. Additionally, we analyzed the spectral data with multivariate data analysis (MVDA) to detect hidden signs of polymer degradation that are not visible with the naked eye.